Preparing bright stocks by hydrogenation



,an an Patented Sept. 11, 1962 tic 3,053,760 PREPARING ill-EIGHT STOQKSBY HYDROGENATTON Alfred M. Henke, Springdale, and Joseph B. McKinley,

New Kensington, Pa, assiguors to Gulf Research 8;

Development Company, Pittsburgh, Pa, a corporation of Delaware NoDrawing. Filed Mar. 4, 1960, Ser. No. 12,696 2 Qlaims. (Cl. 208-264)This invention relates to improved procedure for preparing refinedlubricating oils and in particular to improved procedure for preparingbright stock.

It is well known that lubricating oil stocks can be improved by treatingthem with hydrogen in the presence of a hydrogenation catalyst atelevated temperature and pressure. These reaction conditions areselected so as to result in hydrogenation of minor constituents butwithout resulting in extensive splitting or extensive alteration of thehydrogen-to-carbon ratio. These procedures have been applied to lighterlubricating oils such as distillate lubricating oil stocks in the SAESW-SAE 40 viscosity ranges and to a lesser extent to heavier lubricatingfractions. Although these procedures result in a marked improvement inthe lubricating oil, further advances in this respect are desirable.

This invention has for its object to provide improved procedure forpreparing superior lubricating oils by treatment of lube oil stocks withhydrogen in the presence of a hydrogenation catalyst at temperatures andpressures resulting in relatively little splitting of carbon to carbonbonds. A still further object is to provide improved procedure forpreparing superior bright stock type lubricating oils. Other objectswill appear hereinafter.

These and other objects are accomplished by our invention which includessubjecting a lubricating oil stock which is substantially free ofasphaltic materials to treatment with hydrogen in the presence of ahydrogenation catalyst deposited upon a carrier which is predominantlyEta alumina under reaction conditions which do not result insubstantially splitting to form lower boiling hydrocarbons. We havefound that by operating in this manner a finished lubricating oil havingsuperior properties can be obtained. According to another aspect of ourinvention we subject a crude lube oil feed of the bright stock boilingrange to catalytic hydrogen treatment under conditions designed to givehigh yields of good quality bright stocks.

The charge stock to our process may be any hydrocarbon lubricating oilstock. Thus we may treat distillate type lube oil stocks representingthe lowest boiling portion of the lubricating oil range such aslubricating oils having a viscosity corresponding to spindle oil or 5WSAE. Our invention may also be applied with advantage to anyintermediate boiling range distillate lube oil stock such as any lubeoil corresponding to W SAE, SAE, 30 SAE etc. Our invention is alsoapplicable to hydrocarbons of a heavier type such as those correspondingto bright stock. Bright stocks derived from residual portions ofpetroleum or distillates of the bright stock viscosity range produced byvacuum distillation may be used. When residual stocks are used as feedto the process they should be deasphalted.

A bright stock is frequently a component of lubricating oils, includingthose oils employed in the crank case of internal combustion engines.Such crank case lube oils are ordinarily produced by blending variouscomponents having different viscosities in order to obtain the diiferentSAE grades. For instance a 30 SAE crank case lube oil will frequentlycontain a certain amount of bright stock. The presence of this brightstock may in certain cases, have a deleterious effect because brightstocks are derived from the heaviest portions of the crude and theseheavy portions ordinarily contain components having high carbon residueproperties which result in poor performance during use. Our inventionnot only results in improvement in color, stability, etc., but it alsoresults in a marked reduction in carbon residue. While carbon residueproperties of bright stocks can be improved by conventional refiningprocedures, these procedures are so drastic that they eliminate a largeportion of the bright stock as useful lubricating oil. Therefore theyields are low. Our invention not only yields lube oils and especiallybright stocks having low carbon residues, but it gives such oils inunusually high yields as compared with prior art refining procedures.

The Eta alumina carrier can be prepared advantageously by dehydrating orcalcining Bayerite 01' beta trihydrate of alumina. One such method forpreparing Eta alumina is described by Stumpf et al., Industrial andEngineering Chemistry, Volume 42, page 1398 (1950). While this methodfor preparing Eta alumina is advantageously used, it is to be understoodthat any method for preparing Eta alumina is entirely satisfactory andmay be used in accordance with our invention. Com mercial sources of Etaalumina are available and any such commercial Eta alumina may beemployed in preparing a catalyst for use in accordance with ourinvention. The Eta alumina may contain other forms of alumina such asalpha, beta or gamma alumina. However the carrier should bepredominantly Eta alumina and the higher the purity of the Eta aluminathe better the action of the catalyst.

The hydrogenating component of the catalyst may be any hydrogenatingmetal, any hydrogenating metal oxide, any hydrogenating metal sulfide orany mixture of such hydrogenating catalysts. Thus thehydrogenatingcomponent may be platinum, tungsten oxide, molybdenumoxide, nickel, nickel oxide, etc. We prefer to employ a catalystcomprising a mixture of an oxide and/or sulfide of a group VI left-handcolumn metal with one or more oxides and/ or sulfides or an iron groupmetal. Thus this preferred catalyst may be a mixture of molybdenum andcobalt oxides or sulfides or a mixture of nickel and tungsten oxides orsulfides. The amount of hydrogenating component (determined as themetal) may be between about 0.25 and 30 wt. percent and preferablybetween about 15 and 25 weight percent. Such hydrogenating catalysts arewell known in the prior art as well as their methods of preparation. Anyof these prior art catalysts and any prior art method of preparation maybe employed. Ordinarily it is preferable to form the Eta alumina carrierinto tablets, pellets, etc. and to then impregnate this Eta alumina withaqueous solutions containing the salts of the metals to be used as ahydrogenation catalyst. Thereafter the catalyst is calcined to c nvertthe active component into the oxide. If the sulfide is used, thecatalyst is ordinarily presulfided such as by treatment with a mixtureof hydrogen and hydrogen sulfide at elevated temperature. While weprefer to employ these particular prior art methods of preparation, anyknown method "for preparing hydrogenation catalysts deposited upon acarrier may be utilized.

The procedure of our invention is applicable to the treatment of thelubricating oil stock under reaction conditions which result inrelatively little splitting of the lubricating oil charge stock intolower boiling hydrocarbons. In general these conditions involve theutilization of moderate temperature conditions such as between about 450and 800 F. and preferably between about 500 and 780 F. The pressure isordinarily between about and 5000 psi. and preferably between about 300and 3500 p.s.i. A hydrogen recycle rate between about 100 and 10,000s.c.f./bbl. and preferably between 3 about 500 and 5000 s.c.f./bbl. maybe employed. A space velocity between about 0.2 and 16 volumes of chargeper volume of catalyst per hour, and preferably between about 0.5 and 8may be employed. As is well known in the hydrogenation field, theemployment of low space velocities results in more extensive conversionat any given temperature. It is therefore evident that although theconditions described can in general be employed, the space velocity andtemperature should be so selected that splitting into lower boilinghydrocarbons is not substantial.

EXAMPLE Eta alumina powder, manufactured by Davison Chemical Company,was tableted to form inch size tablets. These tablets were then brokento pass through a and to be retained on a 20 mesh sieve. The brokentablets were calcined by heating in air in an electric muffie furnace to1000 F. in six hours and holding at this temperature for about tenhours. This calcined 10 to 20 mesh Eta alumina support (33.2 parts byweight) was impregnated by the incipient wetness technique With 410parts by weight of an aqueous solution of nickel nitrate hexahydrate andammonium metatungstate. This solution was prepared by using 177.2 partsby weight of 20 percent nickel nitrate solution (calculated as NiO) and221.5 parts by weight of 49.5 percent ammonium metatungstate solution(calculated as W0 and diluting the mixture with 23.2 parts by weightWater. The mixture then contained 8.4 percent NiO and 26.1 percent W0and had a specific gravity of 1.64. The wet impregnated material wasdried at about 250 F. for 24 hours and calcined by heating in air in amuifle furnace to 1000 F. in six hours and holding this temperature forabout ten hours. The finished catalyst contained 17.39 percent tungstenand 5.41 percent nickel. This catalyst was presulfided by contactingwith H containing 10 volume percent H S at a temperature of 600 F. for aperiod of 8 hours. A lubricating oil stock prepared by propanedeasphalting a residual fraction of an Ordovician crude followed byphenol extraction and solvent dewaxing and having a viscosity at 210 F.of 161 secs. SUV, a color- ASTM union of 4-(dilute) and a carbon residueof 0.88 (Conradson), was contacted with hydrogen in the presence of theabove described catalyst under the conditions given in column 1 of thefollowing table.

A second catalyst was prepared using as a carrier a commercial aluminawhich substantially comprised gamma alumina. This catalyst was preparedin the identical manner described above in connection with the catalyston the Eta alumina carrier. Both catalysts had a nickel-to-tungstenmolar ratio of 1:1. This second catalyst contained 17.16 percenttungsten and 5.34 by Weight nickel. This second catalyst was contactedwith the same charge stock as used in column 1 and under the sameconditions. The results are set forth in column 2 of the followingtable.

It will be noted from the above data that the catalyst deposited uponEta alumina resulted in a consistently lower carbon residue than thecommercial alumina carrier. The Eta alumina also resulted in greaterimprovement in color. Thus Eta alumina is a superior carrier for acatalyst used in this reaction.

The above example and especially column 2 thereof illustrates anadditional specific embodiment of our invention. In general thisspecific embodiment involves utilization of any hydrogenation catalystupon any porous catalyst carrier under specific reaction conditionswhich are designed to give a high yield of bright stock having a lowcarbon residue. Thus in accordance with this specific embodiment of ourinvention either a vacuum distillate or residual type bright stock feedis treated with any of the above described hydrogenation catalysts underconditions which are especially designed to give a superior bright stockproduct and in high yield. The hydrogenation catalyst employed in thisspecific embodiment of our invention is preferably deposited upon aporous catalyst carrier which, however, need not be Eta alumina. Thusfor instance, the carrier may be activated gamma alumina, pumice, orother well known porous catalyst supports such as a silica-aluminacracking catalyst which has been deactivated with steam. The conditionsemployed to treat the bright stock feed and give these improved resultsare a temperature between about 500 and 775 F., a pressure between about300 and 3500 p.s.i., a space velocity between about 0.25 and 2.0 and ahydrogen ratio of between about 300 and 5000 s.c.f. per barrel ofcharge.

The preparation of bright stocks using this last mentioned aspect of ourinvention is advantageously applied to residual type lubricating oilstocks. Such stocks should be deasphalted before the hydrogen treatment.While it is satisfactory to first solvent extract the deasphaltedresidual lubricating oil stock in order to remove aromatic constituents,utilizing known solvent extraction methods, it is advantageous toeliminate the solvent extraction step and directly subject thedeasphalted residual lubricating oil stock to the hydrogen treatment.This has the ad vantage that aromatic components normally removed by thesolvent extraction are left in the feed stock to the hydrogenationtreatment. These aromatic components are then converted into high gradebright stock, thus increasing the yield. The pressure utilized in thetreatment of a residual lubricating oil stock to obtain a high yield ofrefined residual type bright stock is preferably a pressure betweenabout 2,000 and 3,500 p.s.i. The other reaction conditions oftemperature, space velocity and hydrogen rate are the same as mentionedin the preceding paragraph in connection with bright stocks in general.When operating to produce bright stocks, whether of the residual ordistillate type, we prefer to employ Eta alumina as a carrier. Also weprefer to employ a mixture of nickel and tungsten sulfides.

We claim:

1. The process for preparing an improved bright stock which comprises incombination contacting a deasphalted residual lube oil stock whichcontains about the same amount of aromatic hydrocarbons as theun-deasphalted stock with hydrogen in the presence of a hydrogenationcatalyst deposited upon a carrier comprising essentially Eta alumina ata temperature between about 500 and 775 F., at a pressure above 2,000and below about 3,500 p.s.i., at a space velocity of between about 0.25and 2.0, and at a hydrogen rate of between about 300 and 5,000s.c.f./bbl. of feed, said conditions resulting in avoidance ofsubstantial splitting reactions and a high yield of refined bright stockhaving a relatively low carbon residue.

2. The process for preparing an improved bright stock which comprises incombination contacting a deasphalted residual lube oil stock whichcontains about the same amount of aromatic hydrocarbons as theun-deasphalted stock with hydrogen in the presence of a hydrogenationcatalyst comprising essentially a mixture of nickel and tungstensulfides composited with a porous support comprising essentially Etaalumina at a temperature between about 500 and 775 F., at a pressureabove 2,000 and below about 3,500 p.s.i., at a space velocity of betweenabout 0.25 and 2.0 and at a. hydrogen rate of between about 300 and5,000 s.c.f./bbl. of feed, said conditions resulting in avoidance ofsubstantial splitting reactions and a high yield of refined bright stockhaving a relatively low carbon residue.

References Cited in the file of this patent UNITED STATES PATENTSKimberlin et al June 18, 1957 Riblett et al. Nov. 17, 1959 Holm et a1.Jan. 12, 1960 Annable et a1. May 10, 1960 Hofiman July 5, 1960

1. THE PROCESS FOR PREPARING AN IMPROVED BRIGHT STOCK WHICH COMPRISES INCOMBINATION CONTACTING A DEASPHALTED RESIDUAL LUBE OI STOCK WHICHCONTAINS ABOUT THE SAME AMOUNT OF AROMATIC HYDROCARBONS AS THEUN-DEASPHALTED STOCK WITH HYDROGEN IN THE PRESENCE OF A HYDROGENATIONCATALYST DEPOSITED UPON A CARRIER COMPRISING ESSENTIALLY ETA ALUMINA ATA TEMPERATURE BETWEEN ABOUT 500* AND 775*F., AT A PRESSURE ABOVE 2,000AND BELOW ABOUT 3,500 P.S.I., AT A SPACE VELOCITY OF BETWEEN ABOUT 300AND 5,000 AND AT A HYDROGEN RATE OF BETWEEN ABOUT 300 AND 5,000S.C.F./BBL. OF FEED, SAID CONDITIONS RESULTING IN AVOIDANCE OFSUBSTANTIAL SPLITTING REACTIONS AND A HIGH YIELD OF REFINED BRIGHT STOCKHAVING A RELATIVELY LOW CARBON RESIDUE.